Extrusion of polymers through a die to form shaped extrudates is a well known process, and is extensively used commercially, see for instance H. Mark, et al., Ed., Encyclopedia of Polymer Science and Engineering, 2nd Ed., vol. 6, John Wiley & Sons, New York, 1986, p. 571-631 and p. 802-824 (fibers), which is hereby included by reference. Items that can be made by polymer extrusion include films, fibers, sheet, strands (including those strands to be cut into pellets for further processing), and shaped profiles. The extrudates are usually essentially continuous, and are often cut into useable lengths.
The extrusion process is one in which the molten polymer is forced through a shaped orifice, and the extrudate is then cooled, usually until solid. The cross section of the extrudate (perpendicular to the flow direction) usually has the same shape as the orifice. Due to the importance of extrusion commercially, improved dies are constantly being sought, so that the process runs more cheaply, and/or with less off-quality production, etc. A particular problem in this process is "die drips", which are small portions of (usually) molten polymer which collect around the die orifice, and which can cause problems of product defects and downtime.
U.S. Pat. No. 4,822,546 describes a polymer extrusion die which is advantageous for use with high flow polymers and wherein the die is part of an underwater pelletizer. There is no mention of the use of this die in other extrusion processes.